One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,8)(6,7)(9,10,14,18)(11,15,19,24)(12,16,22,21)(13,17,23,20)(25,26)(27,28)(29,33)(30,31)(32,36)(34,35)(37,38)(39,40)(1,2,5,8)(3,6,7,4)(11,19)(13,23)(15,24)(17,20)(26,31)(27,32)(33,38)(34,39)(1,2,5,8)(3,4,7,6)(9,11)(10,15)(12,17)(13,21)(14,19)(16,23)(18,24)(20,22)(25,27,30,32)(26,28,31,36)(29,34,37,39)(33,35,38,40)(1,3,5,7)(2,6,8,4)(25,28)(26,32)(27,31)(29,35)(30,36)(33,39)(34,38)(37,40)(1,2)(3,6)(4,7)(5,8)(9,12)(10,16)(11,20)(13,15)(14,22)(17,19)(18,21)(23,24)(25,29,30,37)(26,33,31,38)(27,34,32,39)(28,35,36,40)(1,4,5,6)(2,7,8,3)(9,13)(10,17)(11,21)(12,15)(14,23)(16,19)(18,20)(22,24)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.